326  
FXUS65 KBYZ 221010  
AFDBYZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BILLINGS MT  
310 AM MST TUE JAN 22 2019  
   
SHORT TERM...VALID FOR TDY AND WED
 
 
SHORTWAVE CONTINUES TO TRACK SOUTH AND EAST, AND SNOW HAS TAPERED  
OFF TO SOME LIGHT SNOW OR FLURRIES IN OUR SOUTHERN UPSLOPE AREAS.  
HAVE LET THE REMAINING WINTER WEATHER HIGHLIGHTS EXPIRE.  
 
WE ARE SEEING CLEARING FROM THE NW, BUT AN AREA OF STRATUS  
REMAINS OVER THE EAST HALF OF OUR CWA. THESE LOW CLOUDS SHOULD  
DISSIPATE AND MOVE OUT OF OUR CWA A BIT LATER THIS MORNING. NW  
FLOW ALOFT IS BECOMING ANTICYCLONIC AND WE ARE ALREADY SEEING  
PRESSURE FALLS IN EXTREME NORTH CENTRAL MT. A KLONDIKE CHINOOK  
WILL COMMENCE TODAY AND WINDS WILL INCREASE ACCORDINGLY AT  
LIVINGSTON, BIG TIMBER AND HARLOWTON. IN FACT, WE ARE ALREADY  
SEEING GUSTS ABOVE 20 MPH AT THE LATTER TWO SITES. AS WINDS  
INCREASE WE WILL HAVE TO KEEP A WATCH FOR BLOWING AND DRIFTING  
SNOW. HARLOWTON MISSED OUT ON THIS LAST EVENT, BUT LIVINGSTON TO  
BIG TIMBER DID PICK UP 1 TO 4 INCHES OF SNOW YESTERDAY. THE SNOW  
WAS FAIRLY WET, AND TEMPS WILL CLIMB TO THE 30S TODAY, SO DO NOT  
SEE A SIGNIFICANT RISK OF BLOWING/DRIFTING.  
 
FLOW ALOFT WILL BACK GRADUALLY TONIGHT IN ADVANCE OF THE NEXT  
CANADIAN SHORTWAVE. GRADIENT WILL TIGHTEN WITH THE GFS SHOWING  
15-20MB DIFFERENCE BETWEEN IDA-LWT TONIGHT. THE NW ORIENTED  
CHINOOK WILL BECOME MORE FAVORABLE FOR THE GAP AREAS OVER TIME,  
AND THOUGH THE STABILITY AND MID LEVEL FLOW WILL NOT BE OPTIMAL,  
THERE LOOKS LIKE ENOUGH INGREDIENTS FOR ADVISORY LEVEL GUSTS AT  
LIVINGSTON AND NYE. HAVE ISSUED A WIND ADVISORY FOR THESE AREAS  
BEGINNING THIS EVENING AND RUNNING THROUGH MIDDAY WEDNESDAY. WILL  
ALSO NEED TO KEEP AN EYE ON BIG TIMBER AND HARLOWTON AS GUSTS TO  
AT LEAST 50 MPH ARE EXPECTED THIS AFTERNOON AND TONIGHT.  
 
A MOIST SHORTWAVE EMERGING FROM THE NORTH PACIFIC WILL BRING A  
GOOD PERIOD OF SNOWFALL TO THE BEARTOOTH/ABSAROKA MOUNTAINS FROM  
LATE TONIGHT THROUGH MUCH OF WEDNESDAY NIGHT. LOW LEVEL  
CONVERGENCE, DEEP ASCENT AND A DENDRITIC LAYER SLAMMED AGAINST THE  
MOUNTAINS ALL POINT TOWARD HEAVY SNOW AND HIGH SNOWFALL RATES.  
HAVE ISSUED A WINTER STORM WATCH FOR THE SW MOUNTAINS WITH AMOUNTS  
TO A FOOT OR MORE POSSIBLE. THIS COULD INCREASE AVALANCHE DANGER  
IN THE HIGH COUNTRY.  
 
AFOREMENTIONED PACIFIC SHORTWAVE COMBINED WITH A CANADIAN CLIPPER  
AND COLD FRONT WILL BRING A PERIOD OF SNOW TO OUR LOWER ELEVATIONS  
FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY NIGHT. LATEST MODELS  
BRING IN THE COLD FRONT A BIT SOONER, SO WE SHOULD SEE COLD  
ADVECTION AND ENHANCED SNOWFALL BEFORE SUNSET. FRONT WILL BACK ALL  
THE WAY TO THE FOOTHILLS AND UPSLOPE FLOW SHOULD BRING GREATEST  
AMOUNTS TO WESTERN AND SOUTHERN AREAS. FORECAST SOUNDINGS SHOW A  
MOIST AND DEEPENED DENDRITIC LAYER ALONG THE AXIS OF MID LEVEL  
FRONTOGENESIS. THIS LOOKS LIKE A 2-6 INCH SNOWFALL FOR AREAS FROM  
BILLINGS WESTWARD AND SOUTHWARD. A HEADS UP FOR ANYONE WITH TRAVEL  
PLANS LATE WEDNESDAY. THE THURSDAY MORNING COMMUTE WILL BE  
CHALLENGING AND CHILLY, WITH LOWS IN THE SINGLE DIGITS AND TEENS  
AS A NEAR 1040MB SURFACE HIGH BUILDS OVER EASTERN MT.  
 
JKL  
   
LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON
 
 
UNSETTLED NORTHWEST FLOW LOOKS TO DOMINATE THE LONG TERM WITH  
PERIODS OF SNOW AND WIND. BESIDES SOME LINGERING SNOW SHOWERS  
OVER THE SOUTHERN MOUNTAINS, MOST OF THURSDAY SHOULD BE FAIRLY  
DRY, BEFORE MODELS DROP THE FIRST IN A SERIES OF WAVES THROUGH THE  
AREA STARTING THURSDAY NIGHT AND FRIDAY. THE GFS BRINGS MOST OF  
THE ENERGY AND PRECIPITATION THROUGH THE AREA ON FRIDAY, WHILE THE  
ECMWF IS A BIT QUICKER AND MORE BULLISH, BRINGING PRECIP THROUGH  
THURSDAY NIGHT INTO FRIDAY. HIGH PRESSURE IS THEN PROGGED TO BUILD  
INTO THE REGION FROM THE SOUTHWEST FOR SATURDAY, BEFORE ANOTHER  
SHORTWAVE LOOKS TO DROP THROUGH OUR EASTERN AREAS AND THE DAKOTAS  
SATURDAY NIGHT. A MORE SUBSTANTIAL SYSTEM THEN LOOKS TO DROP IN  
FROM THE NORTH ON SUNDAY BRINGING ANOTHER SHOT OF COOLER AIR AND  
ACCUMULATING SNOW INTO MONDAY, WITH DRIER CONDITIONS RETURNING  
FOR TUESDAY. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE SUNDAY  
TO MONDAY SYSTEM AT THIS TIME.  
 
HIGH TEMPERATURES LOOK TO RANGE FROM THE 20S AND 30S ON THURSDAY,  
WARMING INTO THE 30S AND 40S FOR SATURDAY AND SUNDAY AS DOWNSLOPE  
FLOW AND WINDY CONDITIONS DEVELOP. MONDAY IS PROGGED TO BE COOLER  
WITH HIGHS IN THE 20S FOR MANY AREAS, WITH 30S FOR TUESDAY. STP  
 

 
   
AVIATION
 
 
SNOW WILL GRADUALLY DIMINISH OVER FAR SOUTHEAST MONTANA AND  
NORTHERN WYOMING THIS MORNING. MVFR TO IFR CIGS WILL CONTINUE  
OVER EASTERN AREAS THROUGH THIS MORNING, WITH MOST PLACES  
IMPROVING TO VFR BY 16Z. VFR CONDITIONS ARE THEN EXPECTED THROUGH  
THE REST OF THE DAY WITH SOUTHWEST TO WEST WINDS INCREASING ALONG  
THE WESTERN FOOTHILLS. WINDS GUSTING TO 50 KTS ARE POSSIBLE AT  
KLVM TONIGHT WITH MVFR REDUCTIONS DUE TO BLOWING SNOW. OBSCURATIONS  
WILL INCREASE OVER THE WESTERN MOUNTAINS LATE TONIGHT AS SNOW  
BEGINS TO MOVE INTO THE AREA. STP  
 

 
   
PRELIMINARY POINT TEMP/POPS
 
 
TDY WED THU FRI SAT SUN MON  
-------------------------------------------------------  
BIL 034 026/037 013/034 026/040 027/045 031/043 022/029  
0/N 06/S 82/S 23/W 21/N 14/O 43/S  
LVM 036 027/038 019/036 026/040 025/044 027/042 019/028  
0/Q 26/O 82/S 24/W 21/N 14/O 42/S  
HDN 035 020/037 009/032 020/039 024/044 027/043 017/028  
1/B 07/S 82/S 34/W 32/W 14/O 44/S  
MLS 032 020/033 003/024 018/033 023/039 027/039 014/022  
1/U 04/S 41/B 33/J 22/W 13/O 33/S  
4BQ 032 020/036 006/026 019/035 024/040 026/040 015/023  
1/B 05/S 62/S 33/J 33/W 24/O 44/S  
BHK 029 018/032 902/021 014/030 020/037 024/037 010/020  
1/B 03/S 21/B 33/J 32/W 24/O 43/S  
SHR 034 015/036 011/030 018/038 021/043 024/043 015/026  
1/B 05/S 92/S 34/W 32/W 13/O 54/S  
 

 
   
BYZ WATCHES/WARNINGS/ADVISORIES
 
 
MT...WIND ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO NOON MST  
WEDNESDAY FOR ZONES 65-66.  
WINTER STORM WATCH IN EFFECT FROM THIS EVENING THROUGH LATE  
WEDNESDAY NIGHT FOR ZONE 67.  
WY...NONE.  
 

 
 

 
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